android - 棉花糖权限错误

Question

我正在研究Music Player应用程序，因此我必须从存储卡中获取所有歌曲，然后从存储卡应用程序中成功获取歌曲，并在Lollipop上正常工作。

问题
棉花糖运行时权限我也为棉花糖添加了运行时权限，但应用仍然崩溃..

这是我的完整代码，请告诉我我必须在哪里编写棉花糖的运行时权限。

public class MainActivity extends AppCompatActivity {

    private int STORAGE_PERMISSION_CODE = 23;
    ListView musiclist;
    Cursor musiccursor;
    int music_column_index;
    int count;
    MediaPlayer mMediaPlayer;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init_phone_music_grid();
        if(isReadStorageAllowed()){
            //If permission is already having then showing the toast
            Toast.makeText(MainActivity.this,"You already have the permission",Toast.LENGTH_LONG).show();
            //Existing the method with return
            return;
        }

        //If the app has not the permission then asking for the permission
        requestStoragePermission();
    }

    private void requestStoragePermission() {

        if (ActivityCompat.shouldShowRequestPermissionRationale(this,Manifest.permission.READ_EXTERNAL_STORAGE)){
            //If the user has denied the permission previously your code will come to this block
            //Here you can explain why you need this permission
            //Explain here why you need this permission
        }

        //And finally ask for the permission
        ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},STORAGE_PERMISSION_CODE);
    }

    //This method will be called when the user will tap on allow or deny
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

        //Checking the request code of our request
        if(requestCode == STORAGE_PERMISSION_CODE){

            //If permission is granted
            if(grantResults.length >0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){

                //Displaying a toast
                Toast.makeText(this,"Permission granted now you can read the storage",Toast.LENGTH_LONG).show();
            }else{
                //Displaying another toast if permission is not granted
                Toast.makeText(this,"Oops you just denied the permission",Toast.LENGTH_LONG).show();
            }
        }
    }



    private boolean isReadStorageAllowed() {
        int result = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);


        if (result == PackageManager.PERMISSION_GRANTED)
            return true;


        return false;

    }


    private void init_phone_music_grid() {
        System.gc();
        String[] proj = { MediaStore.Audio.Media._ID,
                MediaStore.Audio.Media.DATA,
                MediaStore.Audio.Media.DISPLAY_NAME,
                MediaStore.Video.Media.SIZE };

        musiccursor = managedQuery(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                proj, null, null, null);
        count = musiccursor.getCount();
        musiclist = (ListView) findViewById(R.id.PhoneMusicList);
        musiclist.setAdapter(new MusicAdapter(getApplicationContext()));

        musiclist.setOnItemClickListener(musicgridlistener);
        mMediaPlayer = new MediaPlayer();
    }

    private AdapterView.OnItemClickListener musicgridlistener = new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView parent, View v, int position,
                                long id) {
            System.gc();
            music_column_index = musiccursor
                    .getColumnIndexOrThrow(MediaStore.Audio.Media.DATA);
            musiccursor.moveToPosition(position);
            String filename = musiccursor.getString(music_column_index);

            try {
                if (mMediaPlayer.isPlaying()) {
                    mMediaPlayer.reset();
                }
                mMediaPlayer.setDataSource(filename);
                mMediaPlayer.prepare();
                mMediaPlayer.start();
            } catch (Exception e) {

            }
        }

    };



    public class MusicAdapter extends BaseAdapter {
        private Context mContext;

        public MusicAdapter(Context c) {
            mContext = c;
        }

        public int getCount() {
            return count;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {


            System.gc();
            TextView tv = new TextView(mContext.getApplicationContext());
            String id = null;
            if (convertView == null) {
                music_column_index = musiccursor
                        .getColumnIndexOrThrow(MediaStore.Audio.Media.DISPLAY_NAME);
                musiccursor.moveToPosition(position);
                id = musiccursor.getString(music_column_index);
                music_column_index = musiccursor
                        .getColumnIndexOrThrow(MediaStore.Audio.Media.SIZE);
                musiccursor.moveToPosition(position);
                id += " Size(KB):" + musiccursor.getString(music_column_index);
                tv.setText(id);
            } else
         tv.setTextColor(Integer.parseInt(String.valueOf(R.color.colorAccent)));
                tv = (TextView) convertView;
            return tv;
        }
    }}

请不要将重复标记为只修改我的许可
谢谢

崩溃报告：
E / AndroidRuntime：致命异常：main
                                                                        流程：com.example.j.musicapp，PID：28606
                                                                        java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.j.musicapp / com.example.j.musicapp.MainActivity}：java.lang.SecurityException：权限被拒绝：正在读取com.android.providers.media.MediaProvider uri content：// media / external / audio / media from pid = 28606，uid = 10161需要android.permission.READ_EXTERNAL_STORAGE或grantUriPermission（）
                                                                            在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:3319）
                                                                            在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3415）
                                                                            在android.app.ActivityThread.access $ 1100（ActivityThread.java:229）
                                                                            在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1821）
                                                                            在android.os.Handler.dispatchMessage（Handler.java:102）
                                                                            在android.os.Looper.loop（Looper.java:148）
                                                                            在android.app.ActivityThread.main（ActivityThread.java:7331）
                                                                            在java.lang.reflect.Method.invoke（本机方法）
                                                                            在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1230）
                                                                            在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1120）
                                                                         引起原因：java.lang.SecurityException：权限被拒绝：从pid = 28606读取com.android.providers.media.MediaProvider uri content：// media / external / audio / media，uid = 10161需要android.permission.READ_EXTERNAL_STORAGE，或者grantUriPermission（）
                                                                            在android.os.Parcel.readException（Parcel.java:1621）
                                                                            在android.database.DatabaseUtils.readExceptionFromParcel（DatabaseUtils.java:183）
                                                                            在android.database.DatabaseUtils.readExceptionFromParcel（DatabaseUtils.java:135）
                                                                            在android.content.ContentProviderProxy.query（ContentProviderNative.java:421）
                                                                            在android.content.ContentResolver.query（ContentResolver.java:502）
                                                                            在android.content.ContentResolver.query（ContentResolver.java:445）
                                                                            在android.app.Activity.managedQuery（Activity.java:2227）
                                                                            在com.example.j.musicapp.MainActivity.init_phone_music_grid（MainActivity.java:100）
                                                                            在com.example.j.musicapp.MainActivity.onCreate（MainActivity.java:35）
                                                                            在android.app.Activity.performCreate（Activity.java:6904）
                                                                            在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1136）
                                                                            在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:3266）
                                                                            在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3415）
                                                                            在android.app.ActivityThread.access $ 1100（ActivityThread.java:229）
                                                                            在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1821）
                                                                            在android.os.Handler.dispatchMessage（Handler.java:102）
                                                                            在android.os.Looper.loop（Looper.java:148）
                                                                            在android.app.ActivityThread.main（ActivityThread.java:7331）
                                                                            在java.lang.reflect.Method.invoke（本机方法）
                                                                            在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1230）
                                                                            在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1120）

Answer 1

这是棉花糖及以上版本的示例代码：

  public static class Utility {
        public static final int MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE = 123;

        @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
        public static boolean checkPermission(final Context context) {
            int currentAPIVersion = Build.VERSION.SDK_INT;
            if (currentAPIVersion >= android.os.Build.VERSION_CODES.M) {
                if (ContextCompat.checkSelfPermission(context, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                    if (ActivityCompat.shouldShowRequestPermissionRationale((Activity) context, Manifest.permission.READ_EXTERNAL_STORAGE)) {
                        AlertDialog.Builder alertBuilder = new AlertDialog.Builder(context, R.style.MyAlertDialogStyle);
                        alertBuilder.setCancelable(true);
                        alertBuilder.setTitle("Permission necessary");
                        alertBuilder.setMessage("External storage permission is necessary");
                        alertBuilder.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                            @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
                            public void onClick(DialogInterface dialog, int which) {
                                ActivityCompat.requestPermissions((Activity) context, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
                            }
                        });
                        AlertDialog alert = alertBuilder.create();
                        alert.show();

                    } else {
                        ActivityCompat.requestPermissions((Activity) context, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
                    }
                    return false;
                } else {
                    return true;
                }
            } else {
                return true;
            }
        }
    }

这是一种检查读取外部存储的权限的方法。请参考代码并进行相应的操作。
希望这可以帮助你。

还要在onCreate方法中添加此代码

 boolean result = Utility.checkPermission(MainActivity.this);